The article presents the results of data comparison for three different electromagnetic systems used for exploration of primary diamond deposits in the territories of mining company «Catoca» in the Republic of Angola. One of these systems is helicopter-borne, the two others are ground based: one transient and one dipole electromagnetic profiling. Data obtained in both time-domain and frequency-domain are compared. It is shown that airborne electromagnetic system is equally informative and has as good resolution as ground methods while measuring responses from small subsurface objects.